Curtain door



United States Patent Blaise DAnka Cleveland, Ohio Nov. 22, 1968 Oct. 6, 1970 Crescent Metal Products, Inc. Cleveland, Ohio a corporation of Ohio Inventor Appl. No. Filed Patented Assignee CURTAIN DOOR 5 Claims, 9 Drawing Figs.

US. Cl

Int. Cl E05d 15/16 Field of Search [56] References Cited UNITED STATES PATENTS 816,496 3/1906 .\lc Kenzie 1. 160/191 2,030,873 2/1936 Hungerford 160/191 2,334,749 11/1943 Burr 160/192 2,336,660 12/1943 West l60/191X 2,926,727 3/1960 Purdy 160/189 3,076,686 2/1963 Warlick 312/297 3,330,611 7/1967 Heifetz 312/297 Primary Examiner Dennis L. Taylor Arlm'ne Bosworth Sessions, Herrstrom and Cain ABSTRACT: A cu formed from a plura rtain door assembly for roll-up doors lity of slats arranged in abutting relationship. The slat forming the upper end of the door is provided with a counterweight to aid in counterbalancing the weight of the slats forming the door. A pair of spring members are secured to one of th e slats intermediate the ends of the door and to a support for the door to aid in operation of the door.

Patentel Oct. 6, 1970 Sheet INVENTOI? 64 4455 d 14/1/44;

Patented Oct. 6, 1970 Sheet 2 012 HTTOQMCYJ CURTAIN noon BACKGROUNDOF THE INVENTION This invention relates to curtain doors and more particularly to a roll-up curtain door for storage containers.

Roll-up doors are utilized to close and to provide access to various containers. They are also utilized to open and close various openings such as entrances to buildings. The roll-up doors heretofore utilized have required complex gears, sprockets, chains andother devices to insure that the door is balanced for easy opening and closing and also to insure that the door will stay in position to provide only limited access to the opening. The weight and complexity of such doors have substantially prevented widespread use of the same particularly in those areas where weight and space considerations are important. For example, curtain doors have not been widely used in portable containers such as restaurant bussingcarts and airline food carriers because of the weight problem. The conventional bussing cart is provided with a hinged door. In many restaurants and hotels the open door presents a hazard to personnel within the area and occupies space which might be better utilized. The conventional airline food carriers are provided with a removable door which must be stored when access to the carrier is required. Such storage presents space utilization problems in the galleys of airplanes. The mechanisms heretofore used to open and close the doors have occupied valuable space in the containers thereby increasing the size and cost of the containers.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a curtain door of simple construction that may be readily opened and closed. A further object of the present invention is to provide an improved curtain door for portable containers for food and other objects. Another object of this invention is to provide a lightweight roll-up curtain door.

This invention contemplates a curtain door assembly for roll-up doors comprising a support for the roll-up curtain door assembly. The curtain door includes a plurality of slats, the first one forming the bottom of the door and the last slat forming the other end of the door with the remaining slats in abutting relationship to each other. Flexible and resilient members are provided to aid in the opening and closing of the curtain door and they are secured to one of the slats intermediate the first and last slat and to the support for the door. The last slat serves as a counterweight for the door and is either heavier than the other slats or a counterweight is firmly affixed thereto.

BRIEF DESCRIPTION OF THE DRAWINGS I In the drawings:

FIG. I is a perspective view ofthe curtain door of this invention with the door in a closed position;

FIG. 2 is a perspective view of the curtain door of this invention in a partially opened position;

FIG. 3 is a perspective view of the curtain door of this invention in a fully opened position;

FIG. 4 is a perspective view to an enlarged scale of a portion of the curtain door ofthis invention;

FIG. 5 is a perspective view to an enlarged scale of the resilient members in relaxed position;

FIG. 6 is a partial perspective view of the bottom of the curtain door;

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG.

FIG. 8 is a cross-sectional view taken along the line 8-8 of FIG. 7; and

FIG. 9 is a partial perspective view of an alternative arrangement of the resilient members.

DETAILED DESCRIPTIONOF A PREFERRED EMBODIMENT Referring now to the drawings, reference numeral 10 indicates in dotted lines the outline of a bussing cart of conventional design having a front 11, a top 12 and a back 13. The bussing cart 10 is also provided with two parallel side panels 14 and a bottom 15 parallel to the top 12. The front 11 of the cart 10 is provided with an opening 16 adapted to be closed by the curtain door 17 of this invention. The curtain door 17 is constructed and arranged to glide in a pair of door tracks 18 which are parallel to each other and are arranged in close proximity to the side panels 14. The tracks 18 are substantially U-shaped in configuration with one leg in contact with the bottom 15 of the cart 10 near the front 11. The other leg of the track is normally spaced from the bottom 15 near the back 13. The tracks 18 are of conventional construction and are substantially channel shaped tracks adapted to receive roller guides 20. secured at each end of the slats 21 forming the curtain door 17.

The slats 2.1 are elongated members of conventional construction arranged in interlocking and abutting relationship as shown in FIG. 8 andthey are supported at each end by the roller guides 20. Each slat 21 is provided with a hook shaped portion 22 along its lower edge and a second hook shaped portion 23 along its upper edge. The hook portion 23 is adapted to be retained within the hook portion 22. With the curtain door 17 in position as shown in FIG. 1, a sufficient number of slats 21 are provided to extend from the bottom 15 to the top 12 of the cart and substantially completely across the top 12. The first slat 21a forms the bottom of the curtain door 17 and the uppermost slat 21b, that is the one most remote from the slat 21a, forms the end of the curtain door 17. The slat 21b may be heavier than the other slats 21 or a counterweight 24 may be rigidly affixed thereto to aid in counterbalancing the weight of the curtain door 17.

One of the slats 21 is selected as a master slat 210 which is near the slat 21b and preferably between the 10th and 16th slat from the slat 21b. The master slat 21c when the curtain door 17 is in its closed position as indicated in FIG. 1, will be located at the top 12 of the cart 10.

To aid in counterbalancing the weight of the door and counterweight, if any, and to assist in opening and closing the door 17 a pair of elongated, flexible and resilient members 25 are provided. In the preferred embodiment the members 25 are elongated springs which may be covered with a cloth or plastic cover 26. The cover 26 will prevent any entanglement of the members 25. The first spring or resilient member 25 is at tached at each end 27 to the master slat 21c by two brackets 28 near the ends of the master slat 216. It is slightly shorter than the distance between the two brackets 28. The second spring or resilient member 25 is secured at each of its ends 30 to brackets 31 which are attached to the back wall 13 of the bussing cart 10 near the top 12. The second spring member 25 preferably engages the first spring member 25 as at 32. A clip or other attaching device may be utilized to couple the two members 25 at 32.

The spring members 25 are dimensioned to be in tension when the door 17 is closed as in the position shown in FIG. 1 and because of the engagement between the two spring members 25 with their ends rigidly secured to the brackets 31 and the master slat 210. they will assume substantially an X-shaped configuration. The springs will function in conjunction with the counterweight 24 and the weight of the slats 21 to hold the door 17 in its closed position as shown in FIG. 1. When the door is to be opened, all that is required is a lifting action on the handle 33 on a slat 21 near the bottom of the door 17 and since each of the slats are engaged with adjacent slats any lifting action on this slat 21 will be transmitted through the adjacent slats, moving the same across the top 12 and down the back 13 between the 2 substantially U-shaped tracks 18. Movement of the master slat 210 permits the two springs 25 to come together and extend substantially across the door as shown in H0. 2 at which point they will be in a partially relaxed condition and will not be exerting any force on the door".

The weight of the slats 21, the counterweight 24 and the friction between the roller guides 20 and the tracks 18 will serve to hold the door 17 in any desired position such as that shown in FIG. 2. Continued upward movement of the slat 21a to complete the opening of the door 17 will result in the master slat 21c passing the brackets 31 and moving down the back 13 thereby reversing the positions of the two spring members 25 and again placing the springs in tension as is shown in H0. 3. The combination of the weight of the counterweight 24 and the tension on the spring members 25 will hold the door 17 in its fully opened position as shown in FIG. 3, and will prevent the door from sliding beyond the desired position on the back of the cart.

At any position of the door 17 there are forces acting on the door tending to move it toward its open and closed positions. Such forces tend to balance the door in any position and comprise the force of gravity on the door and the counterweight and the tension exerted by the resilient members. Also there is friction between the rollers and the tracks. This combination of forces acting on the door is such that the sum of the balance of the forces remains substantially the same irrespective of the position of the door thereby retaining it in its proper position.

The springs or resilient members 25 may be attached as shown in FIG. 9 wherein one end 27 of the first member 25 is attached to the master slat 21c and the other end 27 attached to one of the brackets 31 on the opposite side of the cart 10. The other member 25 issimilarly attached but to the other end of the master slat 21c and to the other bracket 31 in order that the members 25 when under tension as shown in H0. 9 will assume an X-shaped configuration.

ln the illustrated-embodiment the brackets 31 are shown as attached to the cart near the back wall 13. Their location depends upon the height, width and depth of the cart 10, as for example, if the cart is very deep, the brackets 31 will be attached near the center of the top 12. The brackets 31 in the preferred embodiment are affixed to the cart somewhere near the middle of the space through which the master slat 21c travels during the opening and closing of the door 17.

It can be seen from the foregoing that the tension on the spring members 23 materially assists in opening and closing the door 17 of this invention. By the utilization of the curtain door for bussing carts or for portable containers for food such as required by the airlines the necessity for a hinged door or a removable door which must be stored when the container is open has been eliminated. Such a curtain door also makes it possible to fill the upper portion of the cart with dirty dishes and then slide the curtain downwardly to cover the same. While this invention has been described with reference to a cart of a greater height than its depth, it should be understood that this invention may be used with equal facility in carts or storage containers of various widths, heights and depths. The carts or containers, for example, may be high and narrow or low and deep.

It should be obvious from the foregoing that various modifications may be made in this invention without departing from the spirit and scope of the appended claims.

I claim:

1. A curtain door assembly for roll-up doors for opening and closing an opening comprising a support for the door, a first slat forming the bottom of said curtain door and positioned at the bottom of said opening, another slat forming the other end of said door and positioned above and beyond said opening in a plane substantially normal to said opening, a plurality of slats in interlocking relationship extending between said first slat and said another slat to completely close said opening, to extend beyond said opening and adapted to be movable as a unitary structure, a counterweight affixed to said another slat, an elongated, flexible and resilient member secured at both ends to one of said slats intermediate said firstslat and said another slat, a second elongated, flexible and resilient member engaging said first resilient member and affixed to said support for the door, said elongated members dimensioned to be under tension in one direction when said first slat is at the bottom of said opening and be under tension in the opposite direction when said first slat had been moved substantially to the top of said opening, whereby the interrelation between said first slat, said plurality of slats, said another slat, and said resilient members being such as to hold said door in any desired position.

2. A curtain door assembly according to claim 1 wherein said first elongated member forms a loop with its associated slat and said second elongated member extends through said loop and is secured at both ends to the support for said door.

3. A curtain door assembly for roll-up doors for substantially rectangular box shaped enclosures having a substantially rectangular opening in one side thereof comprising, a first slat extending across said opening and forming the bottom of said curtain door, another slat extending across the top of said enclosure and forming the other end of said door, a plurality of interlocking slats extending across said opening and across a portion of the top of said enclosure, said plurality of slats joining said first slat and said another slat into a flexible unitary curtain door, an elongated, flexible and resilient member attached at its ends to one of said slats extending across the top of said enclosure, a second elongated, flexible and resilient member attached at its ends to said enclosure and engaging said first member in interlocking relationship, said elongated members dimensioned to be under tension in one direction when said first slat is at the bottom of said opening and be under tension in the opposite direction when said first slat has been moved substantially to the top of said opening, and said another slat being heavier than said first slat and each of said plurality of slats, whereby the interrelation between said first slat, said plurality of slats, said another slat, and said resilient members being such as to hold said door in any desired position.

4. A curtain door assembly according to claim 3 wherein a counterweight is affixed to said other slat.

5. A curtain door assembly according to claim 3 wherein said elongated members are springs having a sheet of flexible material covering said members. I 

